Belt driven Z-Axis / Worm Gear Mount

by VecteR Dec 17, 2016
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Hello mister! Can you upload more picture of this setup?!.. i dont understamd some parts position.. and i need more picture.. more and better angle (sorry my english is not one of the best good)

To anyone wondering about running this for dual Z axis single motor, you most likely can.
It should be pretty simple. Buy 3 more 20 tooth timing pulley and another 5mm wide 100mm long steel rod (unless you bought a multi pack etc). Print a second motor mount (chop it up if you like to what you need.
You don't need the motor section obviously).
Use two timing pulleys per steel rod and run a closed loop of gt2 belt to the other side to drive the steel rod and thereby the other timing pulley on the rod (that length you will have to figure out yourself and make sure it is tight).

Obviously that is quite a painful process though.

The one major flay of this design is backlash. Unfortunately with a worm gear or any metal on metal screw based movement (like with a standard threaded rod etc) for movement to exist there needs to be wiggle room. This introduces backlash. backlash in a printer is a problem. It isn't a problem if you are only moving in one direction.
But it is a 3d printer, you want your Z axis to move in both directions. Especially if you are using z-hop.

Shouldn't it in theory be better to use a toothed idler on the return pulley?

The link to the BOM doesn't work for me.
Can you please post the details on the main page...?
Many thanks in advance...

I just don't know what to google to find that mating drive gears.

Thx for the comment. The site was down due to a server problem.
The link should work now ;)

With a ratio of 1:20 how is the speed of this solution?

Comments deleted.

If you take the parts from the instructions it's exactly the same as with the threaded rod.

You can change the speeds in the firmware...

Thank You, I might adapt this idea for my printer.

is the resolution still just as good and would it be possible to do a dual version of this?

Hi Leo,

with the parts I used the resolution is exactly the same as with the rod. You do not even have to change the firmware settings.
if the motor turns the wrong way just turn the part where the belt connects to the axis. It´s a belt - one side goes up the other down ;).

Theoretically you should be able to use two of these. Since I have only single motor printers I am not sure how complicated it is to sync dual versions. I guess this is a general question for dual versions and not specific to this design...

Thanks a lot for your reply! Could you please upload some prints you have made since the upgrade? That would be great! Thanks

Hey I like the setup a whole lot, yet when I tried it I got a weird Z-banding issue in the walls of prints. I had tried it out to solve this same issue, but seems to have gotten worse actually.. Any thoughts? How much tension are you needing to put in the belt?


You do not need to put much tension to the belt. The weight of the parts should ensure that it is ok.
If you still have Z-banding issues you should check:

Related to this mod:

  • Are the gears ok?
  • Is the axle straight?

In general:

  • Do you have this issue if you use a different slicer e.g. MatterControl?
  • Have you calibrated the steps of the stepper motor in the firmware correctly? (This is not mandatory/necessary for this mod if the original setting is already correct)
  • Is the frame straight and can you move the parts up and down the z-axis smoothly (no wobbling, scraping .etc)
  • Try to change z-axis motor with extruder motor to make sure it´s not related to a defect of your motor
  • Maybe you need to calibrate the stepper motor voltage (I never needed to do this)
  • Maybe it´s an issue of the stepper driver :(

If you are still not able to fix the problem post a question / pics / settings in the Tevo Tarantula Facebook group. I´m sure someone had the same problem and has found a solution ;)

I got the parts yesterday and put it on today.
It works very well well and no calibrations needed. other then changing the direction of z stepper.
Pictures will come later

Thanks for the positive feedback! In case the axis moves in the wrong direction you can simply turn the x axis connector by 180 degrees - You do not need to change the stepper direction because one side of the belt always moves as desired ;)

Ah yes sorry for not say why i need to program the stepper :b
I liked the design better with the motor the other way :)

Looks great in orange.The way you mount the motor doesn't really make a difference as long as you turn the part where the ends of the belt connect as well ;)

Nice design!
Where did you buy the aluminum gears?

I bought them on Aliexpress. I have added a link to the parts list / sources in the description.

Neat idea to use a worm screw to prevent the carriage to drop when power is off.
I don't know the weight of the said carriage but I would advise to try to have the driving pulley closer to the bearings/frame to reduce the stress.

This is by far the nicest comment I've seen from you.

Good point. If you are concerned that the weight is too high you can rotate the part 180° when you mount it.
Then the driving pulley is 5mm closer to the bearing and the distance bearing<->pulley is about 15mm.
But - as far as I can see - it seems to work pretty well the way it is mounted on my printer.